Methods of making insulated cabinets



June 11, 1957 R. M. KlNTz 2,795,020

METHODS OF MAKING'INSULATED CABINETS Fi led Dec. 50. 1952 I5Sheets-Sheet 1 a n an Inventor* 'Rober-t M. Kim-2,

bg l

His Atnoreg June ll, 1957 R. M. KlNTz I 2,795,020

METHODS OF MAKING INSULATED CABINETS Filed DSC. 30, 1952 I 3Shee-'l'fS-Shee't 2 Inventor: Robert, M.Kir1tz,

HiS Attorneg.

vJune 11, 1957 R M, KlNTZ 2,795,020

METHODS 0F' MAKING INSULATED CABINETS med nec. so, 1952 ssheets-sneet 5Inventor: Rober-t, M.Kint.z, bg Q His Attorney.

nited States Patent O M' 2,795,00 METHODS oF MAKING INSULATED CABiNErsRobert M. Kintz, Millcreek Township, Pa., assignor t General ElectricCompany, a corporation of New York Application December 30, 1952, SerialNo. 328,637

2 Claims. (Cl. 20-101) My invention relates to vacuum insulated cabinetsand more particularly to methods of making vacuum insulated cabinets.

Vacuum insulated Istructures may be of the type described and claimed inthe copending application of Herbert M. Strong and Francis P. Bundy,Serial No. 236,788 tiled July 14, 1951. It is to be understood that myinvention is an improvement over the invention of the Strong and'Bundyapplication and therefore, I do not claim as my invention anything shownor described in said Strong and Bundy application which is to beregarded as prior art Vwith respect to the present application. TheStrong and Bundy empl-oy a compressible iiller material for supportingthe walls thereof. If, in the making of vacuum insulated cabinets, acompressible ller material of a thickness corresponding to thedifference between the dimensions of the inner liner and the outer casewere employed, this compressible filler material would be considerablycompressed by the external pressure upon evacuation of the space betweenthe walls, and the walls would therefore be Iconsiderably distortedbecause of the compression of the insulating material. In accordancewith my invention however, a compressible insulating material of athickness `substantially greater than the distance between the inner andouter walls of the cabinet is employed, so that after evacuation -andresultant compression of the iiller material, it supports the walls withthe proper final spacing and with the walls substantially llat andundistorted. In accordance with my invention a convenient method isprovided for effecting the compression of the ller material duringassembly of parts of the cabinet.

It is an object of my invention to provide improved methods for making acabinet of the vacuum insulated type including improved methods forfacilitating the assembly lof the parts of such cabinets.

Further objects and advantages of my invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming part of this specification.

` In carrying out the objects of my invention, the inner liner is formedwith inclined side walls providing a tapering plug structure and theinsulation placed within the outer case includes similarly inclined sidewalls providing a tapering receptacle for receiving the inner liner.Flexible strips are provided adjacent at least the lower portion of theside walls of the insulation so that these strips are engaged by theinner liner as the liner is inserted and compresses the insulation,whereby any tendency to force the insulation downwardly toward thebottom of the case and thereby to leave voids in the upper portion isminimized. A solid plug or an inflatable bag may be employed forsupporting the walls of the inner liner during this assembly.Alternatively, the insulation may be compressed substantially to size bya plug before insertion of the inner liner to minimize the compressionPatented June 1l, 1957 ice 2 elected by the installation of the innerliner. As an additional alternative the insulation may be placed aroundthe exterior of the liner, compressed substantially to size, and theliner with the surrounding insulation then inserted within the outercase.

For a better understanding of my invention, reference may be had to theaccompanying drawings in which Fig. 1 is a sectional elevation view ofan insulated cabinet made in accordance with my invention.

Fig. 2 is an exploded view lshowing the cabinet of Fig. 1 just prior toassembly.

lFig. 3 is an exploded view similar to Fig. 2 showing a modified form ofmy invention.

Fig. 4 shows one stage of the construction of a cabinet beingmanufactured in accordance with another form of my invention.

Fig. 5 shows the structure of Fig. 4 in another stage of manufacture. n

Fig. 6 shows another modified form of my invention.

Fig. 7 yshows one stage lof a method of manufacture applicable to theform of invention shown in Fig. 6.

Referring to Fig. l, `there is shown an insulating cabinet whichincludes an outer case or wall 1 and an inner liner or wall 2. The outercaseincludes sidewalls and a bottom wall 3 welded to the side walls at 4to complete the outer case. The space between the outer case and theinne-r liner is lled with a compressible heat-insulating material 5,which may be, for example, a glass liber heat-insulating material. Inthe form `s-hown the inner liner 2, like the outer case 1 includes aside wall structure 6 and a bottom wall 7 welded to the side wallstructure at-8 to complete the inner liner. The top edges of the outercase and the inner liner are Welded at 9 to seal the space between theouter case and the inner liner. The space is evacuated in 'anyconventional manner to provide a very low pressure therein. The sidewalls 6 'of the inner liner 2 are inclined inwardly toward the bottom toprovide a liner having a tapering plug structure. The heat-insulatingmaterial 5 has similarly inclined side walls providing a taperingreceptacle structure. The significance of these shapes `of the innerliner and of the heat-insulating material is explained in detail below.

The inner liner and the outer case are shown in the process of assemblyin the exploded view of Fig. 2. As there shown the outer case 1 isreceived within a fixture generally represented by 10 for supporting thewalls of the outer case against distortion or outward bulging duringassembly. The fixture or form 10 has internal dimensions correspondingto the external dimensions of the outer case. Although the walls of theouter case may be yallowed to bulge outwardly as a result of thepressure exerted during assembly, reliance being had upon the evacuationof the space between the outer case and the inner liner for restoringthe shape of the outer case, I refer to mount the outer case in asuitable wall supporting fixture It@ during assembly. Theheat-insulating material 5, which is a compressible material suchV asglass ber, is then placed .within the outer case 1 adjacent the sidewalls and the bottom thereof. While illustrated as a single mass, thisheat-insulating material may most convenientlybe assembled by providingit in the form of batts. One of these batts is placed adjacent thebottom and one batt adjacent each of the four side walls. The battsadjacent the side walls of the outer case are formed with inner surfaces11 inclined inwardly toward the bottorn ends thereof. This provides atapering receptacle for receiving the inner liner 2 which, as describedabove, includes similarly inclined side walls providing a tapering plugstructure.

Since a compressible heat-insulating material is ernploy'ed as a fillermaterial for supporting the walls of the outer case and the inner linerafter evacuation of the space therebetween, it is necessary that thismaterial be subjected to a substantial pressure and substantiallycompressed during assembly; otherwise, the, large external pressureexerted against the walls after evacuation would result in a substantialinward bowing and distortion thereof, detracting from the appearance ofthe tinished cabinet. In order to accomplish this result the thicknessof the heat-insulating material, as illustrated in Fig. 2, issubstantially greater than `the final thickness after assembly of theinnerliner, as illustrated in Fig; 1. yin other words the inner.dimensions of the tapering receptacle Aare substantially smaller thanthe corresponding outer dimensions of the liner. It is necessary thatthe reduction in thickness of `the heat-insulating material, that is thecompression of `the heat-insulating material, -be effected as the innerliner 2 is assembled and further that this be effected without`significantly forcing the heat-insulating material downwardly along thesidewalls which would tend to leave voids at the top portion of thecabinet. The aforementioned tapering structure of the inner liner andofthe side walls of the heat-insulating `material is provided to assistin accomplishing this objective. It will be seen that this structureprovides a mouth at 12 which is greater than the size of the bottom 7 ofthe inner liner so that the bottom of the inner liner may enter freelywithin the mouth 12.

In order to further minimize any tendency to force the heat-insulatingmaterial along the side walls downwardly toward the bottom of thecabinet one or more guide elements 13 are provided adjacent at least thelower portion of the inner surfaces 11 of the side walls of theheatinsulating material. In the form shown, a plurality of spaced strips13 are provided around the entire perimeter of the lower portion of theheat-insulating material, these strips extending inwardly along aportion of the bottom of the heat-insulating material. t It will beapparent, however, that the guide element structure could be provided inthe form of a single pan-like receptacle having slits at the corners toallow for outward movement during assembly of the inner liner.Alternatively, it could also consist of two sheets in overlappingcruciform structure each sheet v extending the full width or length ofthe bottom of the heat-insulating material and including ends extendingupwardly-.along the side walls in the` same manner` as the strip guideelements illustrated in Fig. 2. The guide elements 13 may be made of anysuitable material so long as it is sufficiently flexible to permit thenecessary distortion and outward movement thereof as the inner liner isassembled. The upper ends 14 are extended upwardly along the side wallsof the heat-insulating material a sufficient distance so that thedimensions of a `horizontal plane extending through the top edges 14 ofthe guide elements 13 exceed the corresponding dimensions of the bottomof the inner liner. For example, the dimension illustrated at d in Fig.2 is slightly greater than the corresponding dimension d of the bottomof the inner liner 2. Because of this dimension relationship the bottomlof the inner liner 2 passes within the contines of the guide elements13 before engaging the side walls of the heat-insulating material.Hence, any tendency to force the side wall portion of heat-insulatingmaterial downwardly toward the bottom during assembly, which might besignificant if `the inner liner were allowed to engage the side wallportion of the heat-insulating material directly, is minimized. Theinner liner engages the guide elements 13 and rides therealong, and theguide elements in turn contine the heat-insulating material and directit toward the corresponding side walls of the outer case, minimizing thedownward force exerted against the heatinsulating material. By thisarrangement, therefore, the heat-insulating material is compressed tothe shape and size shown in Fig. 1 while still retaining heat-insulatingmaterial in the space between the outer-case and the inner linerthroughout the full height of the side Walls of the cabinet.

in order to minimize distortion of the inner liner 2 during assembly asolid, preferably wooden, plug 15, shaped to conform exactly to theinterior surface of the inner `liner 2, is provided within the innerliner 2. During assembly a downward force is exerted on the top of theplug 15, as indicated by the arrows in Fig. 2, for urging the innerliner 2 into the receptacle provided by the heat-insulating material 5.As mentioned above, this downward force first brings the bottom of theinner liner into engagement with the guide elements 13 below the topedges 14 of these guide elements. Continued pressure exerted on the topof the plug 15 then forces the inner liner 2 downwardly to its iinalassembled posi tion relative to the outer case 1, compressing both theside walls and the bottom wall of the heat-insulating material 5. Theforce chosen is such as to exert a pressure of approximately 15 poundsper square inch throughout thcVheat-insulating material, since this willthen balance the external force exerted on the walls of the outer caseand the inner liner after the evacuation of the space therebetween.During this assembly, in the form shown, bulging of the walls of theouter case is prevented by the supporting fixture itl and bulging of thewalls of the inner liner is prevented by the supporting plug 15. Afterthe inner liner 2 has been urged downwardly to its assembled positionthe top edges of the outer case and the inner liner are welded, asindicated at 9 in Fig. l. This welding may be accomplished in severalways, al1 well-known in the art. For example, the inner liner may bespot welded to the outer ease in the area indicated at 9, while theouter case is retained Within the supporting fixture 10 and while theload remains on the plug 15. The assembled 'structure may then beremoved from the fixture and the :load removed from the plug 15 and thesealing completed by line welding the top edges together. Alnternatively,.the top edges may be line Welded at 9 while the outer caseis retained in the supporting fixture 10 and while the load remains onthe plug 15, completing the sealing of the outer case to the inner linerat that time. Similarly, the evacuation of the space between the outercase and the inner liner may be effected after the elements have beenremoved from the supporting fixture, as when initial spot welding isemployed, or while the elements are still within the supporting iixture,as when the line welding technique is employed. Where the elements areremoved before evacuation there will be some bulging of the walls of theouter case, but since the spot welding has established the properrelationship of the outer case and the inner liner while within thetixture the walls of the outer case will return to their flat shapeafter evacuation with n minimum of stress in the resulting structure.The evacuation of the space between the outer case and inner liner maybe accomplished in any conventional manner well-,known in the art.

A modified form of my invention is shown in exploded lform in Fig. Thesame numerals have been employed to designate corresponding parts inFigs. l and 2 and in Fig. 3. Referring to Fig. 3, the structure includesan outer case or wall '1, an inner liner or wall 2 and heatninsulatingmaterial S. The side walls of the heat-insulat ing materialare inclined as indicated at 11 and the side walls of the inner linerare similarly inclined as indicated 'at 6 as inthe previous form ofinvention. The form of invention shown in Fig. 3 differs from thatillustrated in Figs. 1 and 2 in 'that an inflatable hollow plug 16 issubstituted for the wooden plug 1S. The plug 16, which may be formed ofrubber, plastic or other suitable intiatable flexible rmaterial, isplaced within the confines of the innerrliner 2. The plug 16 is theninliated to a pressure-sud'icient to resist deformation while acompressive force of'app'roxiinately 15 pounds per square inch isexerted on the compressibleheat-insulating material` 5 during assembly.In other words, the plug 16 is preferably inatados() flated to apressure' somewhat exceedinglS pounds per square inch. In order toconfine the plug within the inner liner 2, a suitable block or closuremember 17 is employed along the top thereof. A passage for inflating anddellating the envelopeof the plug 16 is provided at 18 extending throughan opening in the block 17. The block 17 may be clamped or otherwisepressed into engagement with a shoulder 19 formed on the inner liner 2.After the plug 16 has been suitably inflated a downward force is exertedon the block 17, asindicated by the arrows, urging the inner liner firstinto engagement with guide elements 13, andthen further downwardly tocompress the heat-insulating material, as in the formV of inventionpreviously described. The assembly is cornpleted in the same manner asdescribed in connection with Figs. l and 2.

Another alternative form of my invention is illustrated'in Figs. 4 and5. Again, corresponding parts have been identified with the samenumerals as in the previous figures.Y ln the form of invention shown inFigs. 4 and 5 an inflatable plug 16 corresponding to `that illustratedin Fig. 3, is also employed. This form of invention differs from thatshown in Fig. 3, however, in that the inllatable plugY 16 is utilizedfor precompressing the heat-insulating material 5 before-the insertion`of the inner liner or wall 2. j Thus, as shown in Fig. 4, the inflatableplug 16 is first inserted within the tapcringreceptacle provided by theheat-.insulating material 5. Guide elements or strips'20, correspondinggenerally to the guilde elements 13, are employed.. ln this form ofinvention the strips have been made to extend the full height of theside walls of the heat-insulating material. 5, slightly overlapping -thetop edge thereof and extending also slightly inwardly adjacent thebottom wall thereof. A block 21 corresponding somewhat to the block 17in the form of invention shown in kFig.V 3 Vbut shaped to lit within thetop portion of the outercase or wall 1 is employed adjacent `the top ofthe inflatable plug 16. The block 21 includes an otpening for receivingthe inflating passagelt ofthe plug 16. The plug '16. is inserted withinthe receptacleprovided by the heat-insulating material 5 at least beforeinflation thereof has been completed. The block 21 is then-placedadjacent the top surface of the inflatable plug 16, the block 21 beingpositioned by engagement of the shoulder 22 thereof with the top edge 23of the outer case. The block 21 may be clamped` in any suitable mannerto the outer case or itmay be held in position merely by exerting aforce in the direction of the Aarrows exceeding the upward pressureexerted by the inflatable plug :at its ultimate inllated pressure. Afterthe plug 16 has been assembled within the receptacle provided by theheatinsulating material 5 and the block21 superimposed in the mannerdescribed above, the plu-g is inflated through the passage `18 to apressure of at least approxiamtely l5 pounds per square inchto effectcompression of the heatinsulating material to approximately its finaldimensions. While the compressible heat-insulating material 5 tends toyreturn somewhat toward its original size after the pressure exerted bythe inflatable plug is removed, this tendencyrnay be minimized byapplying a suitable binder to thekmaterial 5 or by heat treating themass in accordance with the invention described and claimed in thecepending application of Alfred G. Janes, Serial No. 303,324, tiledAugust 8, 1952 and assigned to the General Electric Company, theassignee of the present invention. I have found that the tendency of thecompressible heat-insulating materialto reexpand after thisprecompression can also be minimized by subjecting the heat-insulatingAmaterial to the pressure of the inflated plug for several successivetimes. That is, the plug may be inflated as described above to apressure of at least approximately l5V pounds per square inchtorcompress the heat-insulating material toapproxirnately its finaldimensions. The plugmay be deflated and then reinated to the abovepressure to again compress the heat-insulating material. I have foundthat subjecting the heat-insulating material to several such pressureapplications, that is carrying the operation through several cycles asdescribed above, results in a smaller reexpansion of the heat-insulatingmaterial after final removal of the pressure than is the case where'only a single compression of the heat-insulating material is effected.

After the compression of the heat-insulating material has been effectedin the manner described above, the plug 16 is dellated and is removedfrom within the receptacle provided by the heat-insulating material. Theprecompression technique has the advantage that the heatinsulatingmaterial may be inspected before insertion of the inner liner and anydeficiencies or voids corrected at that time.` The inner liner 2 is theninserted in the same manner as in the previous forms of my invention, aplug corresponding to the plug 15 in Fig. 2 or tothe inatable plug 16bein-g preferably employed within the inner liner for supporting theWalls thereof. The guide elements 20 areretained during this assembly ofthe inner liner since the heat-insulating material may be expected toreexpand to a size somewhat exceeding the final size and it musttherefore be recompressed as the inner liner is inserted into itsassembled position. However, this recompression is substantially lessthan the compression necessitated where the heat-insulating material, asin the form of invention shown in Figs. l, 2 and 3 is not precompressedbefore assembly of the inner liner. The completion of the assembly bywelding the top edges of the outer case and inner liner together andevacuation of the space therebetween is accomplished in the same manneras in the previous forms of my invention. While an inflatable plug 16has been employed in the forms illustrated in Figs. 4 and 5, it will beapparent that this method could equally well be carried out using asolid plug similar to plug 15 in lieu of the inflatable plug 16 andblock 21.

Intheforms of invention previously described the heatinsulating materialhas been placed within the outer case toprovide a tapering receptacleland the tapering inner liner has then been inserted within thereceptacle. While this is the preferred form of my invention, myinvention may also be carried out by providing the heat-insulatingmaterial adjacent the exterior walls of the tapering inner liner and byforming the outer case to provide :a tapering receptacle structure. Sucha modified form of my vinvention is shown in Figs. 6 and 7. Thus, inFig. 6 an outer case or wall 24 has been provided including downwardlyand inwardly inclined side walls forming :a tapering receptacle. Aninner liner or wall 2 corresponding to that employed in the previousforms of rny invention is also utilized in the form shown in Fig. 6. Inthe form of my invention shown in Fig. 6 heat-insulating material 25 isprovided adjacent the exterior surfaces of the inner liner ,2. Thisheat-insulating material is of constant thickness throughout its areathereby providing exterior walls 26 which are downwardly and inwardlyinclined in the same manner as the side walls of the inner liner 2. ,Theinner liner and its surrounding heat-insulating material thereforeprovides a tapering plug structure.

*In order to facilitate introduction of the tapering plug structure intothe receptacle provided by the outer oase 24 with .a minimum of voidsresulting from shifting of the heat-insulating material, one or moreguide elements 27, corresponding to the guide elements 13 or 20previously employed, are positioned `adjacent the lower portion of theexposed surfaces of the heat-insulating material 25. In this form of myinvention the tapering plug formed by the inner liner and itssurrounding heat-insulating material Vis then forced inwardly into thetapering receptacle provided by the outer case 24. The outer dimensionsof the tapering plug are substantially greater than the correspondinginner dimensions of the tapering receptacle provided by outer case 24 sothat a substantial compression of the heat-insulating material 25 iseffected during the assembly ofthe liner within the outer c'as e p7 p Asthe taperingplug structure is forced into'the outer ease the guideelements 27 first engage the outer case. These guide elements then ridealong the outer case during the completion of the inward movement of thetapering plug structure into `assembled position within the outer case24, thereby minimizing shifting of the heat-insulating materialparticularly at the bottom corners of the inner liner 2.

In order to minimize outward bulging of the outer case during thisassembly the outer case is preferably supported within a fixture28providing a supporting structure conforming to the shape of the outercase. While for convenience `the assembly has been shown as being`accomplished 'bydownward movement of the inner liner in `the samemanner `as in the previous forms of-rny invention, it will be apparentthat this could be accomplished `in the present form, if desired, byinverting the outer case and effecting the assembly by an upwardmovement of the inner liner and its surrounding heatinsulating materialinto the tapering receptacle provided by `the outer case. In order toprovide a finished appearance a` skirt, corresponding to the generallyvertical side walls of the outer case 1 employed for example in the formshown in Fig. l, may be added to the assem bly, enclosing the taperingside walls of the outer case 24.

As in the form of invention shown in Figs. 4 and 5 the type of structureshown in Fig. 6 may also have the heat-insulating material precompressedbefore actual assembly within the outer case. An arrangement foraccomplishingthis precompression is shown `in Fig. 7. As thereillustrated a supporting fixture 29 having tapering 'walls correspondingto the shape of the outer case 24 is employed. Within this supportingfixture is placed a cup-shaped inatable diaphragm 30. The diaphragm 30has a tube 31 extending therefrom for inflation and deflation of thediaphragm. The diaphragm is shown in Fig. 7 in its inated conditionwhere, as in the form of invention shown in Figs. 4 and 5, it isinflated to a pressure of at least approximately l pounds per squareinch to effect compressionof the heat-insulating material. However, itwill be appreciated that this diaphragm is first inserted within thesupporting fixture 29 in a de ated condition. The inner liner 2 withsurrounding heat-insulating material 25 in an uncompressed condition isthen placedwithin the deflated diaphragm 30. The top of this structureis then closed by a block 32 which engages the top 33 of the supportingfixture 29. An opening 34 is provided in this block 32 for the tube 31.

After the parts have been assembled in this manner, the

diaphragm 30 iis inflated through the tube 31 to a presn sure of atleast approximately pounds per square inch, thereby effectingcompression of the heat-insulating material to the dimensions showin inFig. 7. As in the case of `the block 21, the block 32 may be clamped inplace or held in position by a force exerted in the direction of thearrows in Fig. 7 and exceeding the ultimate iniiated `pressure of thediaphragm 30. Further the block 32 may extend into and till up the spacewithin liner 2 so as to prevent any buckling of the liner walls duringthe compressing of insulation 25. As in the case of the invention shownin Figs. 4 and 5, when the diaphragm is deflated the heat-insulatingmaterial `will tend to reexpand to some extent but not to the originaldimensions. Moreover the precompression may be accomplished `under theconditions described and claimed in the aforementioned Janos applicationin the same manner as suggested in connection with the form ofinvention` shown in Figs. 4 and 5 for minimizing such reexpansion. Alsothe amount of reexpansion may be reduced by applying the pressure of theinflated diaphragm to the heat-insulating material 25 several times insuccession. That is, after the initial compression of theheat-insulating material the diaphragm vmay be deflated and thenreinflated to again apply the same compressing pressure to theheat-insulating material. This process may be repeated several times assuggested above in connection with the form of invention shown in Figs.4 and 5. I have found that by such repeated application of pressure theamount of reexpansion of the heat-insulating material after finalremoval of the pressure may be vsubstantially reduced. After the heatfinsulating material has been precompressed in the manner described abovethe tapering plug structure formed by the inner liner 2 and thesurrounding heat-insulating material is then inserted within the `outercase 24 and the assembly completed in the manner previously described.The guide elements 27 mayalso be employed in completing the assembly.

While I have shown and described specific embodiments of my invention, Ido not desire my invention to be limited to the particular constructionslshown and described, and l intend by the appended claims to cover allmodifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. The method of making a vacuum insulated cabinet which comprisesproviding an inner liner and an outer case, shaping said inner liner toprovide side walls inclined inwardly toward the bottom thereby forming atapering plug structure, placing compressible heat-insulating materialwithin said outer case adjacent the side walls and bottom thereof withthe inner surface of the side walls of said heat-insulating materialbeing inclined inwardly toward the bottom to provide a taperingreceptacle for receiving said inner liner, the inner dimensions of saidtapering receptacle being substantially less than the outer dimensionsof said liner, placing a iiexible guide element adjacent at least thelower portion of the inner surfaces of said side walls of saidinsulating material, placing within said inner liner an inatable hollowplug, inflating said hollow plug to conform to and to support said innerliner, exerting a downward force to move said tapering liner downwardlyinto engagement with said guide element and continuing ythe exerting ofsaid force to urge said inner liner downwardly for compressing saidinsulating material along both the bottom and the side walls, securingthe top edges of said inner liner and said outer case in sealingengagement, and evacuating the space between said inner liner and saidouter case.

2. The method of making a vacuum insulated cabinet which comprisesproviding an inner liner and an outer case, shaping said inner liner toprovide side walls inclined inwardly toward the bottom thereby forming atapering plug structure, placing compressible heat-insulating materialwithin said outer case adjacent the side walls and bottom thereof withthe inner surface of the side walls of said heat-insulating materialbeing inclined inwardly toward the bottom to provide a taperingreceptacle for receiving said inner liner, the inner dimensions of saidtapering receptacle being substantially less than the outer dimensionsof said liner, placing a flexible guide element adjacent at least thelower portion of the inner surfaces of said side walls of saidinsulating material, placing within said inner liner an inflatablehollow plug, inflating said hollow plug to conform to and to supportsaid inner liner, placing a block on the top of said inflatable hollowplug and in engagement with the top edge of said inner liner, exerting adownward force on said block to move said tapering liner downwardly intoengagement with said guide element and continuing the exerting of saidforce to urge said inner liner downwardly for compressing saidinsulating material along both the `bottom and the side walls, securingthe top edges of said inner liner and said outer case in sealingengagement, and evacuating the space between said inner liner and saidouter case.

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UNITED STATES PATENTS 850,143 Donnelly Apr. 16, 1907 699,583 2,067,015Munters Ian. 5, 1937 5 2,108,212 Schellens Feb. 15, 1938 2,164,143Munters June 27, 1939 532,289

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